High-Powered Cyclotron Recirculating Targets for Production of the 18F Radionuclide.
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The production of the 18F radionuclide for Positron Emission Tomography(PET) imaging in diagnostic nuclear medicine procedures is limited by the heat rejection capabilities of present cyclotron target designs. Conventional designs are based on the 18O(p,n)18F reaction in a target employing water isotopically enriched in 18O to greater than 95%. In current high-powered boiling target designs, the water boils in the proton beam strike and the heat is removed by a well-cooled condenser located just above the volume heated by the beam. This technology is limited to approximately two kilowatts of beam power. The most promising approach for increasing production is a recirculating target system in which the heat is rejected through an external heat dissipation system which includes a pump and a heat exchanger. In this work, a feasibility study was performed to determine if such a system would be capable of rejecting power levels above 1–2 kW. Experimentally, it was found that the design tested is capable of operating at beam powers greater than 2.7 kW; however, the data contained herein support the position that 5 kW power levels can be rejected using this target approach. Higher temperatures provided by higher beam powers are required to fully determine the maximum performance of such a system.
targets, cyclotron, recirculating, 18F, radionuclide